In our energy conscious world efficient solar design and engineering have become the norm. All across the country cities have adopted ordinances requiring an assessment of the solar efficiency of new construction. From time to time various states and the Federal government have offered tax benefits and credits for the installation of solar aided systems. When selecting the location of a home on a particular site, it is desirable to know which areas will be sunny in the winter and will be shaded in the summer; or which trees would block the sun. If the structure is to use a solar energy collector, it is essential to know whether the collector will be exposed to sunlight on a year-round basis. The path the sun travels can frequently pass behind trees, hills or other structures, placing portions of a specific site in shadows at sometime of the year and for some portion of each day. It is not only important to know whether anything will obscure sunlight, but also to know how long sunlight will be obscured and at what time of day during what months or what time of year.
Heretofore such information was acquired by using a device like that disclosed in U.S. Pat. No. 4,288,922. That patent discloses a table having an arcurate transparent screen provided with markings which indicate the path of the sun and the time of day for each of a number of specific dates. A viewer is disposed on the table so that someone looking through the viewer could examine the site and know where and when sunlight might be blocked.
In rural settings, as well as some urban settings, it is very inconvenient to transport a table and other paraphernalia around a site. The terrain may be uneven or so removed from civilization that streets and roadways are not available. In such circumstances carrying the table described in U.S. Pat. No. 4,288,922 would be extremely inconvenient. The transparencies described in the '922 patent are easily lost or damaged, and in windy situations may be blown off.